With the rapid development of wireless communication technologies, wireless communication has found wide application in people's life, and people's demand for wireless communication is increasing. To satisfy various applications in daily life, the next generation of mobile communication system (which is generally referred to as the 5G mobile communication system currently) has proposed new service types, e.g., Ultra-reliable and Low Latency Communication (URLLC), Enhanced Mobile Broadband (eMBB) communication, and Massive Machine Type Communication (mMTC).
Because the UE supporting URLLC service (which is called a URLLC UE hereinafter) essentially has the sporadic characteristics in the uplink signal transmission, the BS is unable to timely allocate the uplink radio resource to the URLLC UE for transmitting the uplink signal if the uplink radio resources within the tolerable latency range of the URLLC UE have been scheduled and allocated to the other UEs, especially for transmitting some uplink control signals (e.g., the Hybrid Automatic Repeat Request (HARQ) feedback signal). For those uplink control signals, the BS does not schedule the radio resources for the UE to transmit the uplink control signals in a fixed time-frequency position in relation to the downlink data transmission. Instead, the BS dynamically indicates the radio resources for the UE to transmit the uplink control signals through the downlink control information (DCI).
Besides, the BS may reserve some uplink radio resources for common use by the URLLC UE and the UE supporting eMBB service (which is called an eMBB UE hereinafter) so that the URLLC UE can select an uplink radio resource from the reserved uplink radio resources and transmit the uplink signal immediately on the selected uplink radio resource in an uplink grant-free way depending on the transmission need thereof. However, if the uplink radio resource selected by the URLLC UE has been completely or partially allocated to the other UE (e.g., the other URLLC UE or eMBB UE) by the BS, the collision in uplink signal transmission will occur.
Accordingly, an urgent need exists in the art to provide an uplink radio resource scheduling and allocation mechanism to make the URLLC UE able to timely obtain the required uplink radio resource for transmitting the uplink signal even when the uplink radio resources within the tolerable latency range of the URLLC UE have been scheduled and allocated to the other UE, thereby improving the radio resource utilization efficiency and meeting the requirement of ultra-reliability and low latency.